docs(common-css): add missing import (SAP#6473)

Author: Lukas742

docs/knowledge-base/CommonCSS.mdx

@@ -28,10 +28,11 @@ We recommend using the [@sap-ui/common-css](https://www.npmjs.com/package/@sap-u
 
 [Full Documentation](https://sap.github.io/fundamental-styles/?path=/docs/common-css-content-paddings--docs)
 
-You can import the content paddings by adding the following import to your project:
+You can import the content paddings by adding the following imports to your project:
 
 ```ts
 import '@sap-ui/common-css/dist/sap-content-paddings.css';
+import '@sap-ui/common-css/dist/sap-container-type.css';
 ```
 
 ### Responsive Content Paddings